Gliederung

Diadenosine polyphosphates have been characterised as extracellular mediators controlling numerous physiological effects. In this study diadenosine tetraphosphate (Ap4A), diadenosine pentaphosphate (Ap5A) and diadenosine hexaphosphate (Ap6A.) were isolated and identified in human myocardial tissue. Human myocardial tissue was homogenized and fractionated by affinity-, displacement-, anion-exchange-, and reversed-phase chromatographies. In fractions purified to homogeneity, Ap4A, Ap5A and Ap6A were revealed by matrix assisted laser desorption/ionization (MALDI) mass spectrometry and UV-spectroscopy. These diadenosine polyphosphates were further identified by enzymatic analysis, which demonstrated an interconnection of the phosphate groups with the adenosines in the 5Â´-positions of the riboses. Furthermore, Ap4A, Ap5A and Ap6A were found in human cardiac specific granules and the amount of Ap4A, Ap5A and Ap6A was estimated in the range of about 500 Âµmol/L. In conclusion, Ap4A, Ap5A and Ap6A are present in human myocardial specific granules and may affect heart function in an autocrine loop after being released by stimulation.